*IF* time travel ever gets invented, this trusty device will limit jumps forward or backward to exactly one year, or increments of exactly one year. Otherwise you will find that the Earth has moved in it's orbit and you are left stranded in space, or worse, embedded in the Earth's core.-- simonj, Aug 20 2008 All the problems of time travel were solved once and for all, right here in the bakery! Proof_20of_20Time_20Travel [ldischler, Aug 20 2008] Ah, but then you have to take into consideration (getting a sense of deja vu here, ironically) the solar system's orbit round the centre of the Galaxy and its own movement towards the Great Attractor, and that whole thing about time travel being possible if the Universe as a whole is rotating.
You're only likely to be embedded in the Earth if you go back in time from midday to midnight or forward from midnight to midday and for a "distance" of less than fifty milliseconds.
Two things about time machines. If one which can travel to any point in time is ever invented, the issue is not so much inventing it as finding it, and of course they are always found floating in intergalactic space for precisely this reason.-- nineteenthly, Aug 20 2008 Flash forward to a time in the future when we are completely adept at space travel. A random space traveler discovers the corpse of some poor schlub wearing a 20th century lab coat and goggles, floating in interstellar space. He is theorized to be the victim of his own highly successful time travel device and simultaneous lack of rigorous grounding in theory of same.-- krelnik, Aug 20 2008 Going forward is different than going back though, because of relativity. A particle accelerator moving particles around close to the speed of light sort of moves them into the future and they don't end up in deep space. Going backwards would be different because if it stayed in the "same" place it would create an instant paradox. You place a time machine on a table and send it back, and all of a sudden you can't have done that because it's already there, so going back in time would have to involve something else.
The point being that unless a similar method is used to go back and forward in time, going forward is not going to lead to that scenario, because it's relatively easy. Then again, using the same method both ways would be more elegant.-- nineteenthly, Aug 20 2008 Right, so, suppose you have a way of sending a hen's egg through time. You go to a place on the equator at six in the afternoon local time at an equinox, then set it to travel back in time roughly two and a half microseconds, and set that to repeat indefinitely. You'd end up with a tower of eggs, which would eventually fall over. Therefore that urban myth about balancing eggs is based on fact.
On the other hand, if you did it at six in the morning, you'd end up with an enormous heap of raw scrambled egg with China Syndrome.-- nineteenthly, Aug 20 2008 I think one of the major benefits of time travel is the vast distances you could travel, with respect to *some* frame of reference. Limiting this would seriously effect your corporate sales. And remember, early adoptors of new technology are generally corporations or rich privateers.
It baffles me why people think to go back in time means they arrive at the same place (locally) just at different time.
Let's say every increment of time (in whichever direction) requires a movement in space with respect to some point in space or frame of reference.
Let's say we have the ability to remain stationary with respect to all frames of reference.
Shirley, that's time travel? Douglas Adams (RIP) had a pink knight that did such things...-- 4whom, Aug 20 2008 Unfortunately, although the earth is back to it's same position in it's orbit, the solar system has moved 6,937,920,000 km in it's orbit around the Milky Way and you are left in space with 30 seconds to live.-- wagster, Aug 20 2008 There should also be a law that you can't time travel while talking on a cell phone. (Why not, might as well get all the legal paperwork completed now)-- phundug, Aug 20 2008 // It baffles me why people think to go back in time means they arrive at the same place (locally) just at different time.//
Does it not make sense that travelling through time would 'be' travelling through space? There is not one without the other.-- 2 fries shy of a happy meal, Aug 20 2008 Yes, also remaining absolutely still in space (with respect to all frames of reference) will mean you travel through time.-- 4whom, Aug 20 2008 I made a mistake in my first anno. It's actually seven minutes.
[Wagster], so you're travelling "naked"? You don't have a time machine around you?
There would be no need to use a mobile anyway, seeing as you'd already be in a 'phonebox.-- nineteenthly, Aug 20 2008 Let's assume that time is a dimension much like the three standard spatial dimensions.
I am currently "staying put" - i.e. remaining in the same general area as my laptop, house, wife, coffee and amaretti biscuit because we all follow Newton's laws and fall around the sun / Milky Way / local cluster in the same manner. We remain together as we all travel through the three spatial dimensions and the one time dimension according to the same laws.
I can get in my car and drive east down the road in a straight line, thereby separating myself from them in one spatial dimension. I remain at the same time, latitude and height as everything I was with, despite the fact that we are all tumbling through space together. (Latitude and height are valid dimensions that hold good throughout the universe as you can define your frame of reference as anything you like) I can then drive back west and find that I am reunited with my house, wife, laptop, cold coffee and eaten biscuits. I have moved about through one dimension without changing what has happened in any of the others.
If you find a way to drive a timecar (DeLorean?) along the time dimension, we will not simply stop orbiting the sun whilst everything else goes on ahead of us, everything will remain near us in height, longitude and latitude but will move away from us in time.-- wagster, Aug 20 2008 // In space, no one can hear you say "Oh bugger!"//
Marked-for-Tagline-- po, Aug 20 2008 Exactly, it's time travel - not time 'transportation'. Just like you can't immediately appear somewhere else, but must pass through every point between here and there before you arrive - so it must be for time travel, you must travel through each unit of time from now until whenever, before you have to start rooting in your backback for that dinosaur repellent.
Travelling can be a drag, millions of London commuters will agree - I wonder what time commuting would be like - sure, it would be great to live in a 'commuter time-belt' and travel in to work during the day, returning to the 16th century for the weekends, but on public transport? No thankyou.-- zen_tom, Aug 20 2008 //cold coffee and eaten biscuits//What a majestic glimpse of the future!-- Amos Kito, Aug 20 2008 Sixteenth century commuting is going to be a one way trip unless you have seriously good connections. If you turned up with a time machine, they'd burn you at the stake forthwith, unless you were John Dee or someone seriously into the magickal hegemony of the time.
Some philosophers, notably Henri Bergson, make a fundamental distinction between space and time. His contention appears to be that we are necessarily conditioned to rationalise time as a variety of space, but the fact that it passes betrays that this can't be the whole story. Other dimensions don't pass in the same way that the time ones do. Oddly, he was also very into relativity, so he probably didn't know what he was talking about.-- nineteenthly, Aug 20 2008 So, kind of like a governor on a rental car that limits your top speed? Can you imagine a time machine rental outfit?-- normzone, Aug 20 2008 If I return it yesterday, do I get money back?-- jutta, Aug 20 2008 //Just like you can't immediately appear somewhere else, but must pass through every point between here and there before you arrive - so it must be for time travel//
Ah, but neither statement is true in the quantum world. Small particles can tunnel through space, so that they are first in one place, then in another, and they can go backwards in time too, at least in Feynman diagrams. The problem is getting a whole human body to do it.-- ldischler, Aug 20 2008 I think the real problem has been suggested by [Jutta]. The problem is getting a Visa card transaction to do it.
I guess the next question is how would the rental agency make money on a transaction?
I know - the first clue you'd get that you were going to rent a time machine would be a transaction clearing against your account.-- normzone, Aug 20 2008 Have a look on eBay. You can get ANYTHING on eBay these days ... even time machines ...-- 8th of 7, Aug 20 2008 //The problem is getting a whole human body to do it.//
No bother. I got my body from Friday to Sunday, totally bypassing Saturday. I discovered that time travel gives you a thumping headache.-- wagster, Aug 20 2008 You could get a whole human body to do it if you isolated it from any outside influences, which would make the whole thing rather pointless except for time travelling fetishists.If you paid by credit card, the moment you pay you have zero percent interest, which increases with time. Doesn't that also mean the interest would be negative going back into the past? If it were one percent after a week, say, then two years before you paid it, ignoring compound interest it would be free, and before that they would actually have owed you money. Therefore, you rent a time machine, travel back far enough and collect loads of money from them. This would mean that a time machine rental company which has charges interest on its bills could go bust immediately when it set itself up, which must be why there aren't any.
Which category on eBay? Antiques, presumably. Antique clocks maybe?-- nineteenthly, Aug 20 2008 Aha! Finally a practical use for this. You can use it as an illustration of the difference between odd and even functions. Interest on a credit agreement based on the interval between the initial purchase and the payment due is an even function, whereas interest based on the time since the initial purchase is an odd function.-- nineteenthly, Aug 20 2008 I just want to back in time and sell salt at half price to the Romans. Is that so much to ask?-- 2 fries shy of a happy meal, Aug 20 2008 Why does everyone presume that time travel would also involve dematerialization? Because otherwise YOU COULD NEVER GO BACKWARDS:(thus) YOU CAN NEVER GO BACKWARDS. Time travel forwards is simple enough as we are all doing it all the time to varying degrees and not to a degree that would separate us from other objects or leave us suspended in space. Accelerating this process is easily achieved and the opposite a "slowing" also seems quite possible. If anyone can posit a persuasive case for another way to look at this problem PLEASE POST IT! I would bun it even if i thought it was wrong.-- WcW, Aug 21 2008 //YOU COULD NEVER GO BACKWARDS:(thus) YOU CAN NEVER GO BACKWARDS. //
Is it even possible to conclusively prove that time itself doesn't actually flow in reverse and that we only perceive it as moving forwards? Perhaps the ultimate end effect determines cause and we're just on a rebound wave.-- 2 fries shy of a happy meal, Aug 21 2008 There could be an argument for a specific position having a spacetime line to which time travel is inherently linked and therefore upholding position return . Ending up in space would actually be moving position.-- wjt, Aug 21 2008 If an object travels back in time, it has to dematerialise or move in space. If it didn't, it would immediately crash into itself. I can't see another option. Well, i can, but they're both mad.-- nineteenthly, Aug 21 2008 //I can't see another option. //
The other option is, the object was always moving back in time.-- ldischler, Aug 21 2008 Hang on a sec [nineteenthly], I'm moving forward in time but not crashing into my future self. Why would I crash into my past self moving backwards?-- wagster, Aug 21 2008 That could happen on a small scale, or very improbably, but otherwise entropy indicates the direction. We might be perceiving time as moving forwards rather than in the same way as we perceive there to be left and right in space, but if that's true, it seems implausible that much could be done about it. Seeing the object as moving backwards in time sounds to me like sophistry or reverse entropy, and the latter is improbable, though not impossible, except on a scale where quantum effects become important.-- nineteenthly, Aug 21 2008 Hello [wagster].
Good point, and i think this is the answer: you don't crash into your future self because you aren't there yet. You will only be there when you will be. If you go backwards, you're already there.
Having said that, that's a really interesting observation and i'm going to have to think about that one.
I did have another thought, which was that if you just stopped moving forwards in time, everything else would rush past you into the future and you'd automatically end up in the past.-- nineteenthly, Aug 21 2008 Is that not what happens when the speed of light is attained?-- 2 fries shy of a happy meal, Aug 21 2008 Yes! So, maybe luxons stand still and tardyons move. What about tachyons?-- nineteenthly, Aug 21 2008 Hang on a sec [nineteenthly], I'm moving forward in time but not crashing into my future self. Why would I crash into my past self moving backwards?-- wagster, Aug 21 2008 //The problem is getting a whole human body to do it.//
No bother. I got my body from Friday to Sunday, totally bypassing Saturday. I discovered that time travel gives you a thumping headache.-- wagster, Aug 21 2008 Let's assume that time is a dimension much like the three standard spatial dimensions.
If you find a way to drive a timecar (DeLorean?) along the time dimension, we will not simply stop orbiting the sun whilst everything else goes on ahead of us, everything will remain near us in height, longitude and latitude but will move away from us in time.-- wagster, Aug 21 2008 // In space, no one can hear you say "Oh bugger!"//
Marked-for-Tagline po, Aug 20 2008
Exactly, it's time travel - not time 'transportation'. Just like you can't immediately appear somewhere else, but must pass through every point between here and there before you arrive - so it must be for time travel, you must travel through each unit of time from now until whenever, before you have to start rooting in your backback for that dinosaur repellent.
Travelling can be a drag, millions of London commuters will agree - I wonder what time commuting would be like - sure, it would be great to live in a 'commuter time-belt' and travel in to work during the day, returning to the 16th century for the weekends, but on public transport? No thankyou. zen_tom, Aug 20 2008
//cold coffee and eaten biscuits// What a majestic glimpse of the future! Amos Kito, Aug 20 2008
Sixteenth century commuting is going to be a one way trip unless you have seriously good connections. If you turned up with a time machine, they'd burn you at the stake forthwith, unless you were John Dee or someone seriously into the magickal hegemony of the time.
Some philosophers, notably Henri Bergson, make a fundamental distinction between space and time. His contention appears to be that we are necessarily conditioned to rationalise time as a variety of space, but the fact that it passes betrays that this can't be the whole story. Other dimensions don't pass in the same way that the time ones do. Oddly, he was also very into relativity, so he probably didn't know what he was talking about.-- nineteenthly, Aug 21 2008 Does deja vu count as time travel?-- zen_tom, Aug 21 2008 I still see no case for time travel into the past. Slowing or accelerating your relative timeline seems perfectly possible but I am relatively sure that the past no longer exists in any form and thus cannot be communicated with. Much as we can slow and speed the burning of a candle so can we change the relative pace of time but there is no way to bring back the wax that was burned and burn it again.-- WcW, Aug 22 2008 //A random space traveler discovers the corpse of some poor schlub wearing a 20th century lab coat and goggles, floating in interstellar space.//
[krelnik] may have just solved the paradox of time travel, namely, if it ever becomes possible where are the travellers from the future? Could be that it's not only possible but lethal as well.-- simonj, Aug 22 2008 IIIVMM, IIXX guA ,ylhtneetenin
What i'm about to say is somewhat halfbaked:
There is more than one way to perceive space and time. One of the ways we relate to space is in seeing objects which are behind or in front of us, or to our right or left. Although we could set up Cartesian coordinates with ourselves or some arbitrary point as the origin, there's no way of deciding which side is negative and which positive on either axis. If one turns round, behindness and "in front"-ness swap, but in a different way than left and right. You can't literally reverse left and right, which is why objects in a mirror are less strange than they appear. This is a clue to what's going on. Time is similar. It can be seen as another axis, but that doesn't account for which direction it's going, and except for deciding that now is zero, there is no position either temporally or spatially for one's current position if one thinks of time or space in that way.
Then there is the space and time we actually deal with when we aren't thinking about it in a somewhat scientific or mathematical way, by which i mean the time and space that one "owns" subjectively. In this, there is a here, a now, a past, a future and a left and a right. Imagining time going backwards is similar to imagining walking through a mirror into a looking glass world. They don't happen because space and time aren't like that, but we are conditioned to see them that way because they are useful rather than being an accurate reflection, so to speak of reality.
Relativity suggests that this isn't the whole story, i.e. it's counterintuitive. For instance, the notion of simultaneity is a bit shaky.
Concerning the reality of the past and the future, since we at least imagine ourselves to have freewill, in a sense it's the future which is the imaginary category for us because we conceive it to be undetermined, whereas the past has already happened and the evidence for it is all around us. The only evidence we have for the future is the passage of time, so we see it as empty and yet to be filled with events, whereas we see the past as full of stuff. Therefore, i don't see the future as a place where i would crash into myself, because i think of it as undetermined, that is, empty. By contrast, i see the past as full of stuff, such as a time machine which is already there to crash into.
There's more than this but i think i need to go off and read Heidegger.
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:dekabflah tahwemos si yas ot tuoba m'i tahW-- nineteenthly, Aug 22 2008 //If you find a way to drive a timecar (DeLorean?)//With a name like that, it could only have been invented by a Frenchman.I think the only reason time-travel is impossible, is that the laws of grammar completely break down. (As noted by Douglas Adams)-- coprocephalous, Aug 22 2008 Well, if you could go back in time, wouldn't that destroy the concept of conservation of energy-mass in some way? I know it would somehow break down the theory that there is a finite amount of matter/energy in the Universe.
If we could travel back in time, couldn't we store all the entropy in the Universe inside of a entropy container (just a thought, like Maxwell's demon) and then either send it to ourselves in the past or future?
I also think time travel is impossible just cause of the practical jokes that could be played. I wouldn't like some jerkoff playing a practical joke on me that I've never met yet.-- WhereYouAt, Aug 22 2008 How do you know that entropy itself isn't a practical joke being played on all of us by someone living at the end of time? Seriously though, all the entropy in a container is not entropy because it's a kind of order.-- nineteenthly, Aug 22 2008 Time travel limiter: "You're nicked: You were doing 40 years per second in a 25 years per second zone."-- Ling, Aug 23 2008 random, halfbakery